
package com.barcode.camera;

import android.content.Context;
import android.hardware.Camera;
import android.os.AsyncTask;
import android.util.Log;

import java.util.ArrayList;
import java.util.Collection;

import com.barcode.executor.AsyncTaskExecInterface;
import com.barcode.executor.AsyncTaskExecManager;

/**
 * 自动对焦管理
 * @author 火蚁（http://my.oschina/LittleDY）
 * @created 2014-03-14
 */
final class AutoFocusManager implements Camera.AutoFocusCallback
{
    private static final String TAG = AutoFocusManager.class.getSimpleName();
    private static final long AUTO_FOCUS_INTERVAL_MS = 2000L;
    private static final Collection<String> FOCUS_MODES_CALLING_AF;
    static
    {
        FOCUS_MODES_CALLING_AF = new ArrayList<String>(2);
        FOCUS_MODES_CALLING_AF.add(Camera.Parameters.FOCUS_MODE_AUTO);
        FOCUS_MODES_CALLING_AF.add(Camera.Parameters.FOCUS_MODE_MACRO);
    }
    private boolean active;
    private final boolean useAutoFocus;
    private final Camera camera;
    private AutoFocusTask outstandingTask;
    private final AsyncTaskExecInterface taskExec;

    AutoFocusManager(Context context, Camera camera)
    {
        this.camera = camera;
        taskExec = new AsyncTaskExecManager().build();
        String currentFocusMode = camera.getParameters().getFocusMode();
        useAutoFocus = true && FOCUS_MODES_CALLING_AF.contains(currentFocusMode);
        Log.i(TAG, "Current focus mode '" + currentFocusMode + "'; use auto focus? " + useAutoFocus);
        start();
    }

    @Override
    public synchronized void onAutoFocus(boolean success , Camera theCamera)
    {
        if (active)
        {
            outstandingTask = new AutoFocusTask();
            taskExec.execute(outstandingTask);
        }
    }

    synchronized void start()
    {
        if (useAutoFocus)
        {
            active = true;
            try
            {
                camera.autoFocus(this);
            }
            catch (RuntimeException re)
            {
                // Have heard RuntimeException reported in Android 4.0.x+;
                // continue?
                Log.w(TAG, "Unexpected exception while focusing", re);
            }
        }
    }

    synchronized void stop()
    {
        if (useAutoFocus)
        {
            try
            {
                camera.cancelAutoFocus();
            }
            catch (RuntimeException re)
            {
                Log.w(TAG, "Unexpected exception while cancelling focusing", re);
            }
        }
        if (outstandingTask != null)
        {
            outstandingTask.cancel(true);
            outstandingTask = null;
        }
        active = false;
    }

    private final class AutoFocusTask extends AsyncTask<Object, Object, Object>
    {
        @Override
        protected Object doInBackground(Object... voids)
        {
            try
            {
                Thread.sleep(AUTO_FOCUS_INTERVAL_MS);
            }
            catch (InterruptedException e)
            {
                // continue
            }
            synchronized (AutoFocusManager.this)
            {
                if (active)
                {
                    start();
                }
            }
            return null;
        }
    }
}
